Rare Good News for Beleaguered Florida Keys Corals

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Some much-needed good news for corals in the Florida Keys: After
a decade of devastating declines, populations of staghorn and
elkhorn corals in the Florida Keys National Marine Sanctuary have
remained steady over the last decade.

Coral disease devastated staghorn and elkhorn corals throughout
the Keys and the Caribbean starting in the late 1970s. Severe
coral bleaching also contributed to significant population
declines. Bleaching occurs when water temperatures rise: Corals
expel the symbiotic algae that provide them with their dazzling
colors and their food. When the algae are shed, the white coral
skeletons are left behind.

Dwindling populations prompted the listing of staghorn and
elkhorn coral
as "threatened" on the Endangered Species List in 2006.

Researchers from the University of North Carolina, Wilmington
have monitored the coral reef communities in the marine sanctuary
since 1998. This past summer, the researchers counted and
measured the corals, as well as invertebrates such as urchins and
anemones, at 280 sites off the northern Keys, from Key Largo to
Islamorada.

The count revealed that while populations of the iconic branching
corals remain far below their historic numbers, the surviving
populations of both species have not suffered further declines.

"Our estimates for population sizes for staghorn and elkhorn have
remained relatively constant over the last 10 years, with
millions of staghorn colonies and several hundred thousand
elkhorn colonies present throughout the sanctuary," said UNC
Wilmington researcher Steven Miller, principal investigator for
the project. "These numbers, however, represent a small fraction
of what previously existed throughout the Florida Keys."

The research also indicates that long-spined sea urchins,
important grazers of
seaweed that can kill off corals, also appear to be on the
slow road to recovery. Disease ravaged urchins in Florida and the
Caribbean in the early 1980s.

"Although long-spined sea urchin densities are almost 100 times
less than their levels in the early 1980s, we have documented a
slow but steady increase in their numbers and sizes," said UNC
Wilmington researcher Mark Chiappone.

Urchin sizes noticeably increased in the past 20 years, and
researchers anticipate that with time, increasing urchin numbers
and sizes may help corals to recover on reefs with abundant
seaweed cover.